Temperature response of growth of larval dragonflies - an overview

We review the knowledge about the thermal reaction norms of larval growth in Odonata with a focus on the temperature response function. We re-analyze literature data and present our own results on growth rates of larvae of 14 species of Libellulidae reared at different temperatures. Temperature response curves (TRC) were fitted in order to estimate two relevant components of the thermal reaction, namely the optimum temperature for growth (T-opt) and the increase of growth rate with temperature (Q(10)). We also examined what is known about the thermal minimum (T-min) and the thermal maximum (T-max) for growth to delimit the thermal ranges of odonates. All information indicates that larval growth is generally warm adapted, with species-specific variation of T-opt of 21-31 degrees C, T-min of 8-12 degrees C, and T-max of up to 44 degrees C (the latter being the upper lethal limit, the true T-max for growth remains unknown). The values of Q(10) distinguish some more specialized species, mostly with high T-opt and of tropical origin, and others being more thermal generalists, often being temperate species and/or from lotic habitats. We examine some biotic and abiotic factors affecting the temperature response of growth and we discuss the temperature response in the light of global warming.